Get Airports Within Radius

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To obtain airports within a radius, there are a lot of algorithms that can be used. Take a given airport and then obtain its latitudinal and longitudinal values from a database.

The problem is simple enough: you need to get all the airports that fall within a certain radius. Using the great-circle distance formula and simple trigonometry: let O1, LatLon 1, O2, LatLon2 be the degree in radian, latitude, longitude of two points delimited by radius R in miles.

So, you have distance D as:
D=R*(arcos(cos(O1)*(os(O2)*(LatLon2-LatLon1)+ sin(O1) * sin(O2)

This is based on the assumption that Earth is a perfect sphere. However, Earth is an oblate spheroid because it flattens at its poles due to rotation. This factor introduces a flaw in the formula.

The airports radius proximity search algorithm is still in its developmental stages. Improvements are being sought for accuracy and optimization, but most algorithms that seek to achieve optimization often fail. The worst case scenario occurs when a search is carried out within a large radius with thousands of airports falling within that radius boundary. This would affect and overload the database server if data are not properly indexed